The present invention relates to storage systems for high viscosity materials. More particularly, the present invention relates to a mechanism for diverting high viscosity material into an opening for unloading from the storage system.
Highly viscous materials, such as sludge from waste water treatment, are often stored in silos. The highly viscous materials typically have no free-flow characteristics and need an assist to be moved from one point to another. Various systems have been used for the movement storage and handling of such highly viscous materials.
One common storage facility for sludge and other highly viscous materials is a silo that contains a sliding frame system near the silo floor. A sliding frame silo consists of one or more hydraulic cylinders which reciprocate a frame across the floor to move material into a conveyor located in a channel below the silo floor. FIG. 1 is a perspective view of a typical cylindrical storage silo 12 for holding viscous material, with an outer wall 14 broken away to expose a hydraulically activated slide frame 16 near floor 18 of silo 12. FIG. 2 is atop view of the inside of the storage silo 12 containing slide frame 16. Material stored within silo 12 is discharged by reciprocating slide frame 16 across floor 18 to assist transporting the material to outlet 20 via one or more conveyors 22 positioned in a floor channel beneath the slide frame 16.
Materials stored in silo 12 which are of a high viscosity tend to resist natural gravitational flow. In order to facilitate the movement of such material out of silo 12, a slide frame 16 is used. The slide frame 16 of silo 12 is a simple machine consisting of either one or two hydraulic cylinders driving slide frame 16 in a reciprocating motion across the silo floor 18. Slide frame 16 is configured with a perimeter frame portion 24 connected by central truss 26, support members 28, and cross supports 30 leaving open areas 34 between the structures. As shown, the perimeter frame portion 24 is generally elliptical in shape comprising a mirrored pair of symmetrical chords, however square, round, and other geometries are common depending on the geometry of the floor of the silo 12. The frame portion 24 of slide frame 16 comprises an area less than the area of the floor 18 allowing slide frame 16 to be moved across floor 18 of silo 12 by a hydraulic plunger connected to central truss 26 in the direction of arrows 32. In doing so, perimeter frame portion 24 is intended to agitate the high viscosity material adjacent floor 18. The agitated material then falls through the open areas 34 and through a floor opening 42 into either the conveyor channels or a gate mechanism and is transported out of silo 12. It is desirable to keep conveyor 22 full or a steady flow of material to the gate mechanisms thereby allowing material metering.
The above described silo 12 design provides for a low cost method to store a large volume of material while awaiting final disposal. The sliding frame 16 located in the bottom of the silo 12 allows for metered unloading of stored sludge. Sliding frame or push floor technology within silos is useful for bulk handling processes, including biosolids (biologically derived cake material with greater than 12% solids, or other slurries and sludge with up to eighty percent solids content), coal dust, and wood chips, etc.
Often, however, the stored material bridges to form a cohesive mass, and thus moves as a single mass upon slide frame 16. Bridging of the viscous material occurs when the material viscosity resists flow from normal forces such as gravity. If material bridging occurs, the sliding frame movement may not be adequate to direct the material to the discharge opening. The present invention addresses the problem of material bridging for removal of highly viscous materials from a sliding frame silo storage system.